Power electronics devices are often utilized in high-power electrical applications, such as inverter systems for hybrid electric vehicles and electric vehicles. Such power electronics devices include power semiconductor devices such as power IGBTs and power transistors thermally bonded to a metal substrate. The metal substrate may then be further thermally bonded to a cooling structure, such as a heat sink.
With advances in battery technology and increases in electronics device packaging density, operating temperatures of power electronics devices have increased and are currently approaching 200° C. Accordingly, traditional electronic device soldering techniques no longer provide suitable bonding of semiconductor devices to metal substrates and alternative bonding techniques are needed. One such alternative bonding technique is transient liquid phase (TLP) sintering (also referred to herein as “TLP bonding”). The TLP sintering of a power electronics device utilizes a bonding layer sandwiched between a semiconductor device and metal substrate. The bonding layer at least partially melts and isothermally solidifies to form a TLP bond between the semiconductor device and metal substrate at TLP bonding temperatures (also referred to as sintering temperatures) between about 280° C. to about 350° C. The semiconductor devices and metal substrates have different coefficients of thermal expansion (CTE) and large thermally-induced stresses (e.g., cooling stresses) may be generated between a semiconductor device and metal substrate upon cooling from a TLP sintering temperature. The large thermal cooling stresses due to CTE mismatch between the power semiconductor device and metal substrate may result in delamination between the semiconductor device and metal substrate of a power electronics device when currently known bonding layers are used to form the TLP bond.
Accordingly, a need exists for alternative bonding layers that compensate for thermal cooling stresses between power semiconductor devices thermally bonded to metal substrates via TLP sintering.